This invention generally relates to electricity producing apparatus such as batteries. More particularly, this invention relates to batteries having a primary cell and an integral reserve or backup cell.
Batteries of numerous types and construction have been known to the art for a long time. There are standard sized batteries (e.g. AAA, AA, C, D, 9V, button, etc.), and nonstandard sized batteries. There are primary type batteries, and secondary rechargeable type batteries. There are Leclanche type cells, alkaline cells, mercury cells, etc. Some of the batteries use a nail electrode, some use a carbon rod electrode, while others use. foil. There are batteries which require activation. Activation may be via the use of movable mechanical means which provides relative motion between the electrode and electrolyte, by the introduction of electrolyte via the breaking of frangible means in the battery, or by other mechanisms. Some batteries have single cells, while other batteries have plural cells.
In the electronics age, our society is dependent upon numerous electronic apparatus which require electric power of one type or another. Many of the electronic apparatus which are widely used are portable, including cameras, watches, dictating equipment, computers, radios, toys, calculators, and hearing aids. Such portable electronic equipment requires batteries for operation and typically uses batteries of standard sizes.
The battery powered apparatus cited above, among others, including those equipped with warning devices indicating remaining battery strength or depletion, all exhibit a common deficiency which limits their utility, the consumer satisfaction they deliver, and their market. That common deficiency is the tendency of the battery powered apparatus or system to fail (i.e. to cease to perform acceptably), when the battery reaches a critical point of depletion. This characteristic not only subjects the user to extreme inconvenience and frustration, which is not effectively eliminated by the use of battery testing devices, but it also requires the user to purchase and carry extra batteries of specific sizes if the user wishes to ensure reliable performance and avoid untimely battery and hence apparatus failure. In other words, unless the user is prepared to take inconvenient precautions, the user is subjected to the risk of failure at critically inconvenient moments of the equipment which is to be used. At those moments, the user may not have the ability, readily at hand, to reactivate the system quickly and conveniently.
Mechanical solutions to the problem have been scarce, and practical solutions are essentially nonexistent. Portable battery testers have recently come into use which provide an indication of the relative charge of the battery. These testers, however, fail to provide the user of an indication as to how much life the battery has left vis-a-vis certain equipment. Moreover, it is not always convenient to use the tester to test the batteries in the equipment each time prior to using the equipment or prior to departing with the equipment for use at a later time. As a result, while helpful in certain circumstances, the battery testers fail to provide a mechanism whereby the frequent user of portable electronic equipment will not find himself in the frustrating circumstance of not being able to use portable electronic equipment due to lack of battery power.
Previous solutions have also failed to be effective. For example, in O'Donnell U.S. Pat. No. 3,486,944, a standard sized battery is disclosed as having an active cell and a reserve cell of apparently equal size. A terminal spacer conductor cap is placed over the reserve cell to provide electrical connection, with the reserve cell being out of the circuit. When the active cell is exhausted, the battery is rearranged by the user by dislodging the terminal spacer, sliding the cells out of a perimeter material, rearranging the cells so that the reserve cell replaces the active cell, and reinserting the terminal spacer appropriately. While the arrangement disclosed by O'Donnell may work to provide a reserve cell, it is impractical, as effectively O'Donnell is providing two separate cells in one package. Thus, the cost of the battery would effectively be twice the cost of an ordinary battery. Moreover, by having two separate cells, volume is wasted, and the procedure for rearrangement is inconvenient. Further, since both cells are of equal size, the user is not provided any advantage over placing extra batteries in a sack or the like attached to the apparatus in which the batteries are needed. Also, the reconfiguration of the O'Donnell arrangement is difficult and inconvenient for an ordinary user. In other words, the O'Donnell battery does not provide effective solutions for the user of battery operated apparatus to the problem of batteries which are exhausted at a most inconvenient time.
Batteries having more than two terminals are also known in the art. For example, Goebel U.S. Pat. No. 4,447,504 shows an electrochemical cell having a pair of battery stacks positioned one above the other in a housing and separated by an insulator. The relative thicknesses of the components of the stacks as well as the number of components in the stacks are controlled to achieve different discharge rates and durations of discharge. However, the Goebel battery as conceived and arranged is not a battery which provides an extra reserve, and the Goebel battery is not intended for and is not appropriate for backwards compatibility; i.e., it cannot be used in conventional equipment which requires a positive terminal on one end and a negative terminal on the other end of the battery. Rather, Goebel provides a battery which can power more than one load, and which uses negative terminals on each end and uses the housing as a positive terminal.
Another battery which has more than one cell in a single casing and which has more than two terminals is shown in Schilke U.S. Pat. No. 3,242,009. The stated purpose of the Schilke battery is to provide power to several loads at one time. As such, Schilke is not intended for use as a battery which has an extra reserve and it is not intended for backward compatibility.